The invention relates to lubricating and, if necessary, cooling the rotary bearings of adjustable rotor blades in rotors of axial blowers, such as hot gas blowers, by means of oil introduced into the rotor. The blower comprises a rotor hub receiving the bearings for the rotating of adjustable rotor blades and a hollow drive shaft supporting the hub through which oil can be introduced into the rotor hub.
Such an axial blower is known from German Auslegeschrift No. 24 37 932 corresponding to U.S. Pat. No. 4,046,486. In that blower, at appropriate time intervals, oil is introduced into the interior of the rotor in a quantity such that a cohesive ring of oil rotating with the rotor is formed. From that ring of oil, the individual strut bearings are supplied with oil. As the introduced oil is removed from the hydraulic adjustable mechanism of the rotor blades, it does not have the optimal properties required for lubricating the bearings. Furthermore, it is not evident to an operator when the oil has been used and has to be replaced. Also, the oil is subject to accelerated aging when the rotor is exposed to increased heating when conveying hot gases.